CENTER TWP — A motorcyclist was seriously injured Saturday evening when he crashed into several trees along Route 308 near Holyoke Road, authorities said.

Ronald Litzinger, 36, of Butler was flown by medical helicopter to a Pittsburgh hospital with injuries that emergency crew called “life threatening.”

An Allegheny General Hospital spokeswoman said he was listed in critical condition Monday.

State police said Litzinger was northbound on a Harley-Davidson about 6:30 p.m. when he approached from behind a vehicle on Route 308. The other vehicle was stopped or had slowed to make a left turn onto Belleshire Drive.

Litizinger apparently was unable to stop in time and veered to the left of the vehicle. His motorcycle went off the west side of the road and traveled into a yard, hitting several trees.

He was unresponsive when Unionville volunteer firefighters and a Butler Ambulance Service crew got there. Police said he was not wearing a helmet.

Litzinger had not regained consciousness by the time a medical helicopter landed in a field off the road and flew him to AGH.